1.4 Text Regenerated fibres

There are three types of regenerated fibres：viscose rayon，acetate fibre and protein regenerated fibre.The first two are manufactured from a natural polymer（cellulose），which is usually obtained from wood and cotton linters.The latter may be produced from animal and vegetable proteins.

1.Viscose rayon

Viscose rayon is produced in common by the so-called wet-spinning process through which cellulose is firstly altered from particle or chip shape into a liquid form，and then into filament.^[1] The production flow of viscose rayon mainly includes：cellulose extraction and oxidation，cellulose modification，filament extrusion and after-treatment.Before application to the wet-spinning process，cellulose should be extracted from the raw materials and purified and oxidized.The pure cellulose obtained from cotton linters is usually processed into the form of thin sheet；however，one from wood exists often in the form of wood pulp.^[2] Oxidation is used as a means of reducing the length of cellulose molecule to suitable level.The purified bleached wood pulp or sheets of cellulose are steeped in an alkali solution until the cellulose is converted to soda-cellulose.The alkali pulp is then shredded into alkali cellulose crumb，which is aged for specific time.As the cellulose cannot be dissolved in its original form，the crumbs are then treated with carbon disulphide to produce sodium cellulose xanthate.This is dissolved in dilute sodium hydroxide and forms a honey coloured liquid and aged until required viscosity is obtained.The viscous solution is pumped to the spinning tanks，delivered to the spinning machines.On the spinning machines，the spinning dope is extruded through a spinnerette to form a filament and then into a dilute acid bath in which the filament is coagulated and sodium hydroxide is neutralized.^[3] Finally，the filaments are collected and combined into yarns as end product.In this production flow，there are two important chemical reactions occurring as shown below.

Formation of xanthate ester：

Cell—OH+CS₂+OH^-→Cell—O—CS^-₂+H₂O

Regenerated viscose rayon：

Cell—O—CS^-₂+H⁺→Cell—OH+CS₂

Viscose rayon fibres can be manufactured in different widths by varying the hole size of spinnerette and in different lengths by cutting filaments according to their end-use.Their strength and other physical properties can also be improved by the use of modifiers such as various amines or polyglycol or by changing the process parameter of drawing that orientates the cellulose molecules along the filament axis and increases the strength of the filament.^[4] Many types of viscose and modified viscose have been produced and applied in many fields since 1920s.The significant physical differences between various viscose fibres and cotton include that viscose fibres have a more open structure than cotton and are very amorphous and have high moisture absorption capacity but have low dimensional stability and low strength on wetting.

2.Cuprammonium rayon

Cuprammonium rayon is also composed of cellulose.Cellulose can be dissolved in the solution of copper sulphate mixed with ammonia and sodium hydroxide.The name of cuprammonium is taken from the cupritetrammine hydroxide solution used in the manufacture of the new rayon fibre.In order to make a spinning dope purified，linters are added in the solution of cupritetrammine hydroxide prepared by dissolving the copper sulphate in ammonia；then caustic soda is added to convert the sulphate to corresponding hydroxide.^[5] The spinning solution is pumped through the spinnerette into a funnel through which soft water is running.The movement of water stretches the newly formed filament.The fibres then move to spinning machines，where they are washed，put through a mild acid bath to remove any adhering solution，rinsed and twisted into yarns.

Cuprammonium rayon filaments are produced only on a relatively small scale as the manufacture of the fibre gives rise to a serious environmental problem.Most of the physical properties of the cuprene filaments are similar to those of viscose.Due to high amorphous structure the filaments can absorb more water than cotton.Their tenacity varies with the variation of the fibre's moisture.They have a tenacity of 1.7-2.3g/den in the dry state and 1.1-1.3 g/den when wet.^[6] Cuprammonium rayon has a silk-like appearance.So it is used for the manufacture of the fabrics and garments and lady's hose where it is desired to imitate silk in handle and appearance.

3.Acetate fibres

In this group there are two fibres：diacetate and triacetate fibres.Acetate fibres are also produced from cotton linters or purified wood pulp.Both of them are the modified cellulose fibres.

The production of diacetate fibre includes the following stages：

The natural cellulose is firstly acetylated and converted into cellulose triacetate at temperature up to 50℃ with acetic anhydride in the presence of glacial acetic acid and concentrated sulphuric acid.

[C₆H₇O₂（OH）₃]_n+3n（CH₃CO）₂O→[（C₆H₇O₂）（OCOCH₃）₃]_n+3nCH₃COOH

And hydrolyzed to form cellulose diacetate through an ageing or ripening process in presence of water.

[（C₆H₇O₂）（OCOCH₃）₃]_n+nH₂O→[（C₆H₈O₃）（OCOCH₃）₂]_n+nCH₃COOH

The resulted cellulose diacetate flakes are then dissolved in acetone containing 4% water as the solvent to form the spinning dope，which is filtered and then forced through the spinnerette into a warm-air chamber and the method of spinning is called dry-spinning.^[7]

Triacetate is manufactured from the same raw materials as cellulose diacetate，but the ripening stage in which hydrolysis occurs is omitted in triacetate production.To produce spinning solution，dried acetylated flake is dissolved in methylene chloride and dry-spun into a warm-air chamber.

The molecular weight of cellulose triacetate is higher than that of cellulose diacetate.Both cellulose triacetate molecules and cellulose diacetate molecules are held together by Van der Waals' forces to form amorphous fibres.Both of them are thermoplastic fibre and have certain recovery.They can be dyed with disperse dyes.Diacetate fibre is softer than triacetate and used mainly for apparel fabrics such as satins and taffetas；most cigarette filter tips are made from the cellulose diacetate fibres.Whilst，triacetate fibre is used in a multiplicity of textile application，such as knitted and woven undergarments，skirts and slacks materials，table cloths，furnishing fabrics，etc.

4.Regenerated protein fibres

The raw materials used for the preparation of regenerated protein fibres may be milk，soybeans，peanuts and zein.Sometimes alkaline solutions of gelatin，albumin and other raw materials like waste wool，silk and feathers may be used.Fibrolane and Merinova are made by dissolving casein in sodium hydroxide，and then by extrusion into an acid/salt bath.The fibres formed in this way is stretched as tow and partially stabilized by treatment with formaldehyde.

The general properties of regenerated protein fibres include the wool-like attributes of resilience，warmth and soft handle.Their strength is lower than wool；these fibres do not contain cystin linkage，which results in more open structure.^[8] These fibres are far less successful than hoped and never seriously challenged wool.

New words

1.linters['lintəs]n.棉短绒，棉籽绒

2.after-treatment['ɑ:ftə'tri:tmənt]n.后处理，后整理

3.pulp[pʌlp]n.浆粕，纸浆 vt.使化成浆粕 vi.变成浆粕

4.soda-cellulose['səudə'seljuləus]n.碱纤维素

5.shred[∫red]n.碎片，破布 v.撕碎，切碎

6.age[eidʒ]v.老化 n.寿命

7.dope[dəup]n.黏稠物，浆，涂布漆胶，纺丝原液

8.coagulate[kəu'æɡjuleit]v.凝结 adj.凝结的

9.neutralize['nju:trəlaiz]v.使中和，使平衡

10.polyglycol[,pɔli'ɡlaikɔl]n.聚乙二醇

11.orientate['ɔ:rienteit]v.取向，定向

12.wetting['wetiŋ]n.湿，变湿

13.ammonia['æməunjə]n.氨，氨水

14.acetylate[,æsiti'leit]v.酰基化

15.ripening['raipəniŋ]n.熟，变熟，熟化工艺

16.acetone['æsitəun]n.丙酮

17.chamber['t∫eimbə]n.室，箱，盒

18.thermoplastic[,θə:mə'plæstik]adj.热塑性的 n.热塑性塑料

19.apparel[ə'pærəl]n.衣服，装饰

20.satin['sætin]n.缎，缎纹织物

21.taffeta['tæfitə]n.塔夫绸，平纹皱丝织品

22.undergarment['ʌndə,ɡɑ:mənt]n.内衣，贴身衣

23.slacks[slæks]n.宽松的长裤，便裤

24.soybean['sɔibi:n]n.大豆

25.zein['zi:in]n.玉米蛋白

26.gelatin['dʒelətin]n.凝胶，明胶，动物胶，全力丁

27.albumin[æl'bjumin]n.清蛋白，白蛋白

28.Fibrolane['faibrəulein]n.菲帛罗纶（商品名，一种酪蛋白纤维）

29.Merinova[mə'ri:nəuvə]n.梅里诺瓦（商品名，一种酪蛋白纤维）

30.casein['keisi:in]n.酪蛋白，干酪素

31.tow[təu]n.丝束，纤维束，落纤，短亚麻

32.formaldehyde[fɔ:'mældi,haid]n.甲醛

33.cystin['sistin]n.胱氨酸

Phrases and expressions

1.wet-spinning process 湿纺工艺

2.production flow 生产流程

3.carbon disulphide 二硫化碳

4.sodium cellulose xanthate 纤维素黄原酸钠

5.xanthate ester 黄原酸酯

6.copper sulphate 硫酸铜

7.cupritetrammine hydroxide 氢氧化四氨合铜

8.acetic anhydride 无水醋酸，醋酸酐

9.glacial acetic acid 冰醋酸

10.sulphuric acid 硫酸

11.methylene chloride 二氯甲烷

12.far less 远不及

Notes

[1] Viscose rayon is produced in common by the so-called wet-spinning process through which cellulose is firstly altered from particle or chip shape into a liquid form，and then into filament.

黏胶纤维通常由湿纺工艺生产。在湿纺工艺中纤维素首先由颗粒或片状变成液态，然后加工成长丝。

这里，“which”指“wet-spinning process”。

[2] The pure cellulose obtained from cotton linters is usually processed into the form of thin sheet；however，one from wood exists often in the form of wood pulp.

从棉短绒获得的纯纤维素通常被加工成薄片状，而从木头中获得的纯纤维素则常以木浆的形式出现。

这里，“one”指“pure cellulose”。

[3] On the spinning machines，the spinning dope is extruded through a spinnerette to form a filament and then into a dilute acid bath in which the filament is coagulated and sodium hydroxide is neutralized.

在纺丝机上，纺丝浆液经纺丝头被挤出，形成细丝并进入稀酸浴中，结果是细丝被凝结，氢氧化钠被中和。

[4] Their strength and other physical properties can also be improved by the use of modifiers such as various amines or polyglycol or by changing the process parameter of drawing that orientates the cellulose molecules along the filament axis and increases the strength of the filament.

通过使用各种氨、聚乙二醇化合物等改性剂，或改变拉伸工艺参数调整纤维素分子沿丝轴的取向，黏胶纤维的强力及其他物理性能都能得到提高。

[5] In order to make a spinning dope purified，linters are added in the solution of cupritetrammine hydroxide prepared by dissolving the copper sulphate in ammonia；then caustic soda is added to convert the sulphate to corresponding hydroxide.

为了使纺丝浆液纯化，可将棉短绒加入到预先准备好的溶有硫酸铜的氨水溶液即氢氧化四氨合铜溶液中；然后加入烧碱将硫酸盐转化为相应的氢氧化物。

[6] They have a tenacity of 1.7-2.3 g/den in the dry state and 1.1-1.3g/den when wet.

其干强为1.7～2.3g/den（0.15～0.20N/tex），湿强为1.1～1.3g/den（0.10～0.11N/tex）。

这是一句省略句。完整句为“They have a tenacity of 1.7-2.3g/den in the dry state，and they have a tenacity of 1.1-1.3g/den when they are wet”。

[7] The resulted cellulose diacetate flakes are then dissolved in acetone containing 4% water as the solvent to form the spinning dope，which is filtered and then forced through the spinnerette into a warm-air chamber and the method of spinning is called dry-spinning.

最后，将纤维素二醋酸酯薄片溶解于含水4%的丙酮溶剂中形成纺丝浆液，过滤，并通过纺丝头将丝压入热空气室，这种纺丝方法叫干法纺丝。

[8] Their strength is lower than wool；these fibres do not contain cystin linkage，which results in more open structure.

这些纤维不含二硫键，这使其结构相较羊毛更开放，其强力则低于羊毛。

句中“more open structure”是相对“wool”而言，该句等同于“more open structurn than wool's”。

Exercises

Ⅰ.Answer the following questions.

1.What types of regenerated fibres are classified？

2.What stages are included in the production flow of viscose rayon？

3.What are the physical differences between various viscose fibres and cotton？

4.What is the origin of the name of cuprammonium？

5.What is dry-spinning？

6.What is the definifion of raw materials of regenerated protein fibres？

Ⅱ.Translate the following sentences into Chinese.

1.The production flow of viscose rayon mainly includes：cellulose extraction and oxidation，cellulose modification，filament extrusion and after-treatment.

2.As the cellulose cannot be dissolved in its original form，the crumbs are then treated with carbon disulphide to produce sodium cellulose xanthate.

3.The significant physical differences between various viscose fibres and cotton include that viscose fibres have a more open structure than cotton and are very amorphous and have high moisture absorption capacity but have low dimensional stability and low strength on wetting.

4.Fibrolane and Merinova are made by dissolving casein in sodium hydroxide，and then by extrusion into an acid/salt bath.

Reading material Tencel

Tencel，which is called lyocell，is a regenerated cellulose fibre.It is produced from purified conifer wood pulp through solvent spinning process，in which the purified cellulose is dissolved in the solvent of N-methyl amine oxide to form spinning dope，then the spinning dope is filtered，and then extruded through a spinnerette to form a filament.The procedure of the manufacture of Tencel fibre is shown as follows：

Pulp→solvent→spinning→washing→aftertreatment→drying.

The solvent used the manufacture of Tencel is atoxic and more than 99.5% of it can be reclaimed and re-used.So the manufacture of the fibre does not give rise to any environment problem and is known as‘green process’.

The physical properties of Tencel are given in Table 1-4.

Table 1-4 physical properties of Tencel

Tencel fibre can be degraded by the action of microbe，so it is also considered as‘green fibre’.Tencel fibre has high tensile strength and high moisture absorption capacity.It can provide good wearing performances.It blends well with cotton，wool，silk and other fibres.Fabrics made from it or its blends possess a soft hand，pearl-like luster and good drape.It is primarily used for lady'underwear，shirts skirts and slacks，etc.which are associated with fashion.